1. Field of the Invention
The present invention relates to a heat transmission device used for an air conditioner and so on.
2. Description of Prior Art
Heat transmission devices generally have such a construction that a heat transferring medium is confined in a pipeline to utilize change in phase between liquid and vapor of the medium; specifically, heat absorbed at a heat receiving part is transferred to a heat radiating part to be radiated.
FIG. 1 shows a conventional heat transmission device disclosed, for instance, in Japanese Unexamined Utility Model Application No. 66381/1952, in which a reference numeral 1 designates a heat receiving part connected to the upper part of the pipeline; a numeral 2 designates a heat radiating part arranged vertically in the lower portion of the pipeline; numerals 3A, 3B designate first and second check valves which allow fluid to flow in only one direction and a numeral 4 designates an accumulator. There are provided a pipeline 5A between the heat receiving part 1 and the heat radiating part 2, a pipeline 5B between the heat radiating part 2 and the first check valve 3A, a pipeline 5C between the first check valve 3A and the second check valve 3B and a pipeline 5D between the second check valve 3B and the heat receiving part 1; thus, all the pipelines constitute a looped pipeline, namely a closed pipeline. The accumulator 4 and the pipelines connected to the accumulator 4 contain a suitable amount of a working fluid 6 such as freon, methyl alcohol as a heat transferring medium. At the side of the accumulator 4 and above the heat receiving part 1 in the pipeline 5D, there is provided a sealed chamber 7 which is so constructed that as shown in FIG. 2, a reservoir 8 is pivotally supported in the sealed chamber 7 so as to be turned around a supporting point O and when there is no liquid in the reservoir 8, the center of gravity G.sub.1 shifts below the supporting point O so that an opening of the reservoir is directed upward; on the other hand, when there is a predetermined amount of liquid in the reservoir 8, the center of gravity G.sub.2 shifts above the supporting point O so that the opening of the reservoir 8 is automatically directed downward by turning of it around the supporting point O. In FIG. 1, when assuming that the working fluid 6 in liquid phase is referred to as liquid 6A and the working fluid 6 in gaseous phase is referred to as vapor 6B, the liquid 6A is filled in the pipelines at the actuation of the device.
Now, if heat is supplied to the heat receiving part 1, there is produced a high pressure vapour 6B corresponding to the temperature of the liquid 6A in the heat receiving part 1 to cause pressure difference between the heat receiving part 1 and the accumulator 4. Since high pressure condition is produced in the heat receiving part 1, the liquid 6A in the pipeline 5A, the heat radiating part 2 and the pipeline 5B flows into the accumulator 4 whereby pressure in the accumulator 4 is gradually increased.
The vapor 6B produced in the heat receiving part 1 is fed through the pipeline 5A to the heat radiating part 2 where it is cooled and emits heat of condensation to become liquid. Liquefaction of vapor is restricted by both temperature in the heat receiving part and temperature in the heat radiating part. As a result, the pressure of the vapor 6B in the heat receiving part 1, the pipeline 5A and the heat radiating part 2 is the saturated vapor pressure corresponding to temperature of the intermediate of the heat receiving part and the heat radiating part. Accordingly, the pressure of the accumulator 4 is maintained at the level of the saturated vapor pressure during continuation of vaporization of the liquid 6A in the heat receiving part 1.
In this condition and during feeding of the vapor 6B produced in the heat receiving part 1 to the heat radiating part 2 for liquefaction, heat in the heat receiving part 1 is transferred to the heat radiating part 2 and the transfer of heat is continued until there is no liquid 6A in the heat receiving part 1. When the liquid 6A is entirely vaporized in the heat receiving part 1, the pressure of the vapor 6B in the heat receiving part 1, the pipeline 5A and the heat radiating part 2 is lowered due to the temperature of the heat radiating part 2, with the result that there causes pressure difference between the accumulator 4 and the heat receiving part 1. Since pressure in the accumulator 4 is higher than in the heat receiving part 1, the liquid 6A stored in the accumulator 4 is circulated to the heat receiving part 1 through the second check valve 3B. In this case, the liquid 6A does not reach the heat receiving part 1 immediately and it is temporarily stored in the reservoir 8 of the sealed chamber 7 interposed in the pipeline 5D. Namely, when the reservoir 8 contains a predetermined amount of the liquid 6A, the center of gravity G.sub.2 shifts above the supporting point O so that the reservoir 8 is turned to discharge the liquid 6A to the heat receiving part 1 at once. As a result, a large amount of the liquid 6A can be supplied to the heat receiving part 1 whereby the heat receiving part 1 is effectively actuated. By repeating the operations as above-mentioned, heat from the heat receiving part 1 located at the higher portion can be transferred to the lower heat radiation part 2 without using any power.
In the heat transmission device of this kind, however, when the liquid 6A in the heat receiving part 1 is entirely vaporized to produce a pressure difference between the accumulator 4 and the heat receiving part 1, the liquid 6A is once stored in the accumulator 4 and then is supplied to the heat receiving part 1. Accordingly, a stream of the vapor flowing to the heat radiating part 2 must be stopped. As a result, the quantity of heat to be transferred from the heat receiving part 1 to the heat radiating part 2 is decreased or stopped thereby causing pulsation during the transfer of heat.